How to Change a Dirt Bike Chain

MotorcycleUSA Staff | May 8, 2015

There comes a time when you need to replace your dirt bike chain and sprockets. Stock equipment often wears out quickly so keep a close eye on that drive train. One way to tell if your chain and sprockets are burnt up is to pull the chain away from the rear sprocket. If it pulls away and shows a significant amount of sprocket tooth, time to replace both, you don’t want to install a new chain on worn sprockets. If the chain moves side to side excessively, replace both it and the sprockets, especially if you can push it all the way over into the side knobs of the rear tire.You can also use a chain stretch tool (or a ruler) to see exactly how much your chain has stretched. A 520 chain with a 5/8” or 15.875mm pitch should not measure more than 259mm when measuring center of pin to center of pin over 16 lengths on a non O-ring chain. The max distance on an O-ring chain is 256.5mm. If your equipment is worn out and hammered, change it out.

Removing or tightening the counter shaft sprocket nut is easier with the chain on and using the rear brake to hold it in place.

If you have an impact wrench it makes removing the counter shaft nut easy.

Start by removing the counter shaft sprocket nut before you remove the chain, especially if you don’t have an impact wrench. You can use the rear brake to keep the counter shaft sprocket from turning so you can remove the nut. If your sprocket is held on by a circlip, use circlip pliers to tackle the job. When reinstalling and tightening the nut on your new countershaft sprocket, use the chain on method so you can use the rear brake to keep the sprocket from turning. In case you don’t have your owner’s manual, manufacture torque recommendations are as follows: Honda 23 ft-lbs with Loctite, KTM 44 ft-lbs with Loctite, Yamaha 54 ft-lbs with Loctite, Kawasaki 450 93 ft-lbs without Loctite.

The master link can be removed using pliers as shown to push the clip off.

Remove the clip once you’ve pushed off the pins.

Sometimes the side plate needs some love to come off the pins. A screwdriver can be used to help pry it off.

Removing the master link can be done a few different ways. A common way is to use a pair of pliers and squeeze it off as shown. You can use a screwdriver to push it off but that isn’t as consistent as the plier method. Sometimes the side plate needs some help from a screwdriver to pry off.

This is a sign of a very worn out chain. This is way to much side play.

Use the old chain to help determine the proper length of the new chain.

This chain was severely worn out! Save the old chain, you are going to use it to measure your new one. Line up the new chain next to the old one. Make sure you start at one end and keep the pins lined up. If you just lay them next to each other the stretched old chain with give you a false reading. You are matching the number of links. This will also clearly show you how stretched your old chain really was.

A proper chain tool makes removing chain links an easy job.

Once the chain tool has pushed the pin almost all the way out the excess links will easily pull off the chain.

There is more than one way to skin a cat, but the easiest way to take links out of a chain is with a chain tool. We use Motion Pro’s PBR chain tool, which can handle rivet chains that do not have master links. The other way to remove extra links when replacing your chain is a grinder, grinding down the pin and side plate a little and use a hammer and punch to get the pin out. The use of a chain tool is much easier and safer. Instructions included with the chain tool are clear and easy to follow for pushing the pin out of the side plates.

Before installing the new chain the axle adjusters will need to be turned in to properly adjust for the shorter length of the new chain.

Feeding the new chain into position before install the master link.

Before installing the chain, turn in the chain adjusters, your new chain, even though it is the same number of links will be shorter since it isn’t stretched out. Feed the chain around and get ready to install the master link.

With the master link in place install the side plate.

The side plate often requires a little help to fully find its resting place. Pliers are key.

Use pliers to get the master link clip into position. Be careful not to shoot the clip across the garage.

The new side plate on the master link can be tight when reinstalling, especially on an O-ring chain so use some pliers to help squeeze it into position. To install the master link clip use pliers to squeeze it on. Install the clip with the opening facing away from the direction of rotation. If the opening of the master link is facing the direction of rotation it can catch and rip off. Not good for having fun on your dirt bike. Adjust your chain according to the manufacturer’s recommendations and of course tighten your axle nut!

The old stock sprocket was very worn when compared to the new Renthal in the background, freshly installed.

We went with Renthal sprockets and chain. Renthal recommends blue Loctite on the sprocket bolt threads when reinstalling the nuts and bolts. Recommended sprocket bolt nut torque is about 25 ft-lbs. You can see just how worn out our old stock sprocket was when compared to the new one.